[edom31]

Hello - my 135/2.5 has some specs behind the front element that I know I can easily clean off. The problem is that I cannot get that stubborn nameplate out! I've really forced my spanner, to no avail. It won't budge.

I tried getting to it from behind, however, after removing the inner ring that holds the second element in place, that element does not want to come out!

Is there any cemented pieces there? Based on the schematic I do not think that elements 1 -2 are cemented together - but are they cemented to the body?

What's up with my nameplate? is it glued that anyone knows?

Should I try a bit of lighter fluid? I am hesitant to do that in case it penetrates but does not allow me to take the nameplate ring off and thus it may evaporate inside leaving a haze behind.

I do not think it is worth sending it out for CLA, since this is the only issue with the lens.

thanks for suggestions.

[Not a Number]

It may have been worked on before and someone used a thread lock or some other adhesive. Try warming it up with a hair dryer or using a tiny amount of acetone on the threads. Apply with a fine spotting brush or a toothpick.

[marcusBMG]

No info in the lens repair database. A u-tube video of the 135mm f3.5 disassembly shows the nameplate unscrewing in a normal manner.
Double check for any small grub screws that might be locking it on. as per prev, use eg acetone/MEK judiciously along the join (nb minimum quantity, this may well also dissolve the plastic...) and +1 warming things up. good luck

[edom31]

MEK

What is this, If I may ask?

as per prev, use eg acetone/MEK judiciously along the join (nb minimum quantity, this may well also dissolve the plastic...) and +1 warming things up. good luck

It may have been worked on before and someone used a thread lock or some other adhesive. Try warming it up with a hair dryer or using a tiny amount of acetone on the threads. Apply with a fine spotting brush or a toothpick.

thank you both for the responses... I will try with a small brush (few of the hairs) with the acetone and heat

[mkgd1]

What is this, If I may ask?





thank you both for the responses... I will try with a small brush (few of the hairs) with the acetone and heat

Methyl Ethyl Ketone. A strong and toxic lacquer thinner. Home depot has it

[bwgv001]

chemically very similar to acetone; but more dangerous to us.

[edom31]

chemically very similar to acetone; but more dangerous to us.

So acetone it is...

Lighter fluid wont do it then I reckon...

[marcusBMG]

You could try lighter fuel first, if it's just some dirt/greasy stickiness then that could work. But I don't think lighter fuel dissolves thread locker.
When I got an element stuck at an angle in a tamron 200mm I ended up going heavy duty and put the lens in the oven (worked too)! I would try eg covering the end of the lens with a small leakproof polythene eg ziplock bag and dipping in hot water.

[Not a Number]

Lighter fluid will not dissolve lacquers or thread lock. Lacquers are commonly used as a thread lock as it "breaks" easily enough when you want it to.

[edom31]

Lighter fluid will not dissolve lacquers or thread lock. Lacquers are commonly used as a thread lock as it "breaks" easily enough when you want it to.

You could try lighter fuel first, if it's just some dirt/greasy stickiness then that could work. But I don't think lighter fuel dissolves thread locker.
When I got an element stuck at an angle in a tamron 200mm I ended up going heavy duty and put the lens in the oven (worked too)! I would try eg covering the end of the lens with a small leakproof polythene eg ziplock bag and dipping in hot water.

chemically very similar to acetone; but more dangerous to us.

Thanks people!

I will try to hold the lens near my table-top electric over for a few seconds to heat it up, the do acetone if needed.

[pentaxus]

Acetone is good. MEK is illegal in some parts of the US.

[paulh]

I unscrewed the nameplate from my ST 28/3.5 (58mm) by pressing the butt of a small glass against a playtex rubber dishwashing glove placed over the lens. The nameplate unscrewed easily.

[edom31]

I unscrewed the nameplate from my ST 28/3.5 (58mm) by pressing the butt of a small glass against a playtex rubber dishwashing glove placed over the lens. The nameplate unscrewed easily.

I've done this, even with rubber stoppers.

The 135/2.5 is weird - the nameplate rests at a difficult angle; nothing better than spanner to take it out and still does not budge.

I hope heat can do the trick!!!!

[mkgd1]

I've done this, even with rubber stoppers.

The 135/2.5 is weird - the nameplate rests at a difficult angle; nothing better than spanner to take it out and still does not budge.

I hope heat can do the trick!!!!

Let us know if you get it off. We are all waiting with baited breath.

[Riggomatic]

I've done this, even with rubber stoppers.

The 135/2.5 is weird - the nameplate rests at a difficult angle; nothing better than spanner to take it out and still does not budge.

I hope heat can do the trick!!!!

The SMC-K 300 has a steep angle on the name plate as well. I used a fruit cup container, with black tape around the edge to add the grip to the ring.


SMC-K 300 f4 Hood Felt Repair - PentaxForums.com

You could try 1-1/2 PVC pipe coupling (schedule 40 around $1 at home depot), with black tape around the end. In case you have access to those items.

Take the lens with you to double check the fit .